The strait's bathymetry is varied, with the Laurentian Channel creating a deep trench through its centre, and comparatively shallow coastal waters closer to Newfoundland and Cape Breton Island. These bathymetric conditions have been known by mariners to cause rogue waves. The steep slope of the Laurentian Channel was the site of a disastrous submarine landslide at the southeastern end of the strait, triggered by the 1929 Grand Banks earthquake and leading to a tsunami that devastated communities along Newfoundland's south coast and parts of Cape Breton Island.[1]

A strategically important waterway throughout Canadian and Newfoundland history, the strait is also an important international shipping route, being the primary waterway linking the Atlantic with inland ports on the Great Lakes and St. Lawrence Seaway.

In October 1942, German U-boat U-69 torpedoed and sank the unlit Newfoundland ferry SS Caribou, killing 137 people.[2] Then on 25 November 1944 HMCS Shawinigan was torpedoed and sunk with all hands on board (91 crew) by U-1228.